Indexing head
A dividing head is a special vice to workpieces for machining in, and repeated in order to turn exact angular measurements and to fix it.
Use
A dividing head is used in metal cutting to machine a workpiece at specific angular positions. With the help of a dividing attachment Editing can be made as drilling patterns, such as holes around a full circle unevenly distributed, however, reproducible.
Similarly, radial edits are made as multiple groove on a shaft ( Example: Two keyways offset to a shaft by 120 °).
Another application is the surfacing of regular profiles such as splines and serrations.
Construction
A dividing head can be driven by hand and is then usually used on conventional machine tools.
For electric motor drive can be part of the apparatus generally well integrated into the CNC control a machine, so that automatic processes are possible. Especially for the production of profiles with many partitions, this is of great advantage.
Simple indexing units consist of a base plate and a rotatable portion on plate which is positioned by simple notches in certain angular positions. It usually detents are only a few, fixed, predetermined possible.
In more complex indexing units to set ( almost) any angle is attached to a worm gear the subpanel. This is driven by a worm ( worm gear ), which in turn is rotated manually by a crank handle or by an electric motor.
For the manufacture of pitches having a handle apparatus, the handle is locked in the recesses of a perforated disk. The perforated discs have a predetermined number of equally spaced holes which are arranged in a circle. Depending on the number of different, not just regular divisions can be made . Usually have perforated discs several partial circuits that can be realized by different radii on the same disc.
When the crank to reach a position part no complete revolution must be rotated, but for example 2 each full turns and 20 holes on the 30 - hole circle, take the so-called "scissors " to help. This consists of two rotatable about the crank pointers so set that the first link is applied to the side of the index pin engaged. The second arm is then adjusted to 20 locking holes in the rotating direction. This tool eliminates the error-prone counting the index holes and thus serves to process safety.
Frequently, part worm gear on a little play. In order to reduce feature indexing attachments via a clamping device.
Example of use
It is a gear having 31 teeth are made with the aid of a dividing head.
- In the indexing unit used 180 full crank rotations are required to rotate the table to a full rotation of 360 ° (1 crank revolution = 2 ° rotation of the table ).
- For 31 pitches accordingly the table each division by (360 ° / 31 = 1119/31 ° ) ≈ 11.613 degrees must be rotated.
- These are 5,806 turns of the crank ( 1119/31 ° / 360 ° * 180 = 525/31) ≈ required.
- Is expected as decimal instead of the correct fractions, rounding errors are inevitable. It is then determined in a partially apparatus belonging table, which bolt pattern is suitable to the desired pitch. From the break statement, a bolt circle with 31 holes results directly ( since 31 is a prime number ).
- The table shows that all the turns of the crank and an additional 25 holes are necessary for division 5 on the 31er - hole circle.
- The pitch trimmer is adjusted such that the one limb bears on the latched pin, and the other points to the hole 25 in the rotational direction.